[all-commits] [llvm/llvm-project] 642124: [Uniformity] Fixed control-div early stop (#139667)

[Junjie Gu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6421248c959b809efff22773c98b115aac3f6a79
      https://github.com/llvm/llvm-project/commit/6421248c959b809efff22773c98b115aac3f6a79
  Author: Junjie Gu <junjie.gu at intel.com>
  Date:   2025-05-29 (Thu, 29 May 2025)

  Changed paths:
    M llvm/include/llvm/ADT/GenericUniformityImpl.h
    A llvm/test/Analysis/UniformityAnalysis/AMDGPU/branch-after-join.ll
    M llvm/test/Analysis/UniformityAnalysis/AMDGPU/irreducible/diverged-entry-headers-nested.ll
    A llvm/test/Analysis/UniformityAnalysis/AMDGPU/irreducible/hidden-post-dom.ll
    A llvm/test/Analysis/UniformityAnalysis/AMDGPU/phi_div_branch.ll
    A llvm/test/Analysis/UniformityAnalysis/AMDGPU/phi_div_loop.ll
    A llvm/test/Analysis/UniformityAnalysis/AMDGPU/unstructured-branch.ll

  Log Message:
  -----------
  [Uniformity] Fixed control-div early stop (#139667)

Control-divergence finds joins by propagating labels from the divergent
control branch. The code that checks the early stop for propagation is
not correct in some cases.

This PR, also included changes from ssahasra, fixes this issue by
stopping no early than the post-dominator of the divergent branch.

https://github.com/llvm/llvm-project/issues/137277

---------

Co-authored-by: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>



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